474 MR. W. C. WILLIAMSON ON THE MICROSCOPIC STRUCTURE OF THE 
Fig-. 13. Vertical section of the upper half of the same scale, made at right angles to 
the lateral line. Magnified 100 diameters. 
Fig. 14. Horizontal section of part of the same scale, made in the direction of the 
line, fig. 1'2 ef. 
Fig. 15. Vertical section of part of a scale of Megalichthys Hihhertii. Magnified 
80 diameters. 
PLATE XLIL 
Fig. 16. Horizontal section of part of the surface of the scale of Megalichthys Hib- 
heriii. Magnified 60 diameters. 
Fig. 17. Vertical section of part of a scale of a small species of Megalichthys. 
Magnified 110 diameters. 
Fig. 18. Vertical section of the lower part of a scale of Megalichthys Hibhertii, made 
at right angles to the lateral line! Magnified 10 diameters. 
Fig. 19. Horizontal section of the laminae, fig. 15 i, Megalichthys Hibbertii. Mag- 
nified 300 diameters. 
Fig. 20. Oblique horizontal section of the upper part of a Diplopterus. Magnified 
27 diameters. 
Fig. 21. Upper surface of a large scale of Holopty chins sauroides, natural size. 
Fig. 22. Inferior surface of the same scale. 
Fig. 23. Vertical section of a scale of Holopty chins sanroides, taken in the direction 
of the dotted line, fig. 22 c. Magnified 30 diameters. 
Fig. 24. Vertical section of part of the scale of a species of Holoptychius, made nearly 
in the direction of the line, fig. 22 c, only verging more towards the centre 
of the scale. Magnified 30 diameters. 
Fig. 25. Horizontal section of the surface of the opercular bone of Macropoma Man- 
telli. Magnified 25 diameters. 
Fig. 26. Vertical section of part of the same opercular bone, taken parallel to the 
lateral line of the fish. Magnified 70 diameters. 
PLATE XLIII. 
Fig. 27. Vertical section of parts of two scales of Macropoma Mantelli, made parallel 
to the mesial line. Magnified 25 diameters. 
Fig. 28. Vertical section of a row of large dermal teeth, from the centre of a scale of 
Macropoma Mantelli. Magnified 18 diameters. 
Fig. 29. Horizontal section of the surface of the internal osseous viscus of Macro- 
poma Mantelli. Magnified 350 diameters. 
Fig. 30. Vertical section of the parietes of the same viscus, taken in the direction of 
its long axis, and parallel to the mesial line. Magnified 350 diameters. 
